i have a 2002 ranger edge,3.0. 67500 miles oil changed regularly.drive to and from work with an every other weekend drive through the country side.
last week i drove to work next thing i know it is missing real bad and when accelerated would rattle. since it started figured i would drive home! big mistake! that rattle got deeper and then motor froze!
i dropped a valve and did not know it. and the deeper sound was the piston breaking half.
anyone have an idea why this would happen? besides my valve spring breaking.

 

your valve keepers might have broke in half and released the valve. or you had a weak valve that broke beneath the keeper.